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Gas detection is vital in different fields including environmental applications, clinical analysis, and homeland security. To perform these tasks the sensors need to be stable, sensitive, selective, operating at room temperature, rapidly responding, and easy to regenerate. On the other hand, most chemical sensors often suffer from a lack of selectivity, i.e., reacting more or less similarly to a collection of substances. As a result, these sensors may lead to false alerts. Even worse, the molecules to be detected could be masked by some interfering compounds which may result in failure to detect the targets. The goal of this research is to develop a portable gas-sensing device that integrates a zeolite/dye unit with an optoelectronic detector. At nano-scale the sensor is expected to be more accurate, more sensitive, and can better differentiate and detect one chemical component in a mixture of different gases. This could be achieved by incorporating fluorescent dyes into the zeolites' cavities, measuring gas absorption, desorption and photo-chromic interaction of dye and gases, interfacing the zeolite/dye sensor arrays with light source and electronic detectors and fully integrating the sensor arrays into a portable unit. This research addresses many of the above-sated threads. The highly fluorescent organic dye, nile red, was successfully included in the supercages of different zeolites Y (ammonium Y, hydrogen Y, and sodium Y) via chemical reaction. The research also developed an effective method to clean the synthesized inclusions, which is a combination of ultrasound and centrifuge. The cleaned inclusions were baked to remove any gases and/or moisture trapped inside the zeolites' structure. The spectra of the baked inclusions were used as references. The cleaned inclusions were optically characterized in terms of light absorption and fluorescence emission. When exposed to acetone, ethanol, methanol, and de-ionized water, the fluorescence emission spectra of zeolite-sodium-Y/nile-red inclusion showed a similar spectral shift compared to the reference spectrum. On the other hand, the fluorescence emission spectra of zeolite-hydrogen-Y/nile-red inclusion and zeolite-ammonium-Y/nile-red inclusion showed different spectral shifts compared to the reference spectra. This shows the successful proof of encapsulating the nile red dye in zeolites Y's cages, cleaning the zeolite/nile-red combinations, and measuring the desorption and fluorescence emission of the combinations. The optical characteristics of the nile red adsorbing to the external surface of the zeolites Y were studied as well. The research also included the design of the optical system to excite the sensing elements (zeolite/nile-red inclusions), and to collect the fluorescence response, the design and simulation of electronic circuits to condition and process electrical signal, and overall design of an integrated gas detector onto a pressed ceramic optical bench. / Electrical and Computer Engineering

Yes / In order to meet the environmental legislations related to sulfur content, it is important to find an alternative techniques for deep removal of sulfur components from fuels. So, in this study, a novel nano-catalyst based on iron oxide (Fe2O3) as active component prepared over composite support (γ-Alumina + HY-zeolite) is developed here for efficient removal of sulfur compounds from fuel via oxidation process. The precipitation method is employed first to prepare the composite support and then the impregnation method is utilized to generate a novel synthetic homemade (Fe2O3/ composite support) nanocatalysts that has not been developed in the literature (iron oxide over composite support). The characterizations of the prepared catalysts display that the surface area of the catalyst increases with increasing the amount of Y-zeolite in composite support. The effectiveness of the catalysts is tested by utilizing oxidative desulfurization (ODS) operation under several operating conditions. The results of the experimental work show that the activity of oxidative desulfurization enhances with increasing Y-zeolite, temperature, and batch time under moderate operating conditions. The oxidative desulfurization efficiency followed the order: CAT-1 < CAT-2 < CAT-3. The CAT-3 performed the high removal of sulfur compounds (90.73%) at 100 min and 423 K. The best values of the kinetic parameters of the ODS process are then determined based on experimental data and model based techniques within gPROMS package. Finally, the reactor model is used to determine the optimal operating conditions while maximizing the removal of sulfur compounds leading to cleaner fuel. Where, 99.3% of the sulfur removal has achieved at batch time of 190.6 min, temperature of 543.56 K and initial sulfur content at 0.8668 wt% in the presence of CAT-3 based on the optimal kinetic parameters (order of reaction (n) of 1.9865719, activation energy (EA) at 29.942 KJ/mol and pre-exponential factor (ko) with 622.926 wt-0.9865719. min-1).

Made available in DSpace on 2014-12-17T15:42:15Z (GMT). No. of bitstreams: 1 SeverinoHSF_DISSERT.pdf: 1697537 bytes, checksum: d7338ec77a9bb83dfa28e39f146cdab3 (MD5) Previous issue date: 2014-01-24 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Three studies were performed using tailings kaolin for the synthesis of zeolite A. The first synthesis of zeolite A was performed using a kaolin waste generated from the beneficiation of kaolin for paper production process was studied. The kaolin waste was thermally activated at a temperature range of 550-800?C. For comparison was performed a synthesis pattern of Zeolite A(procedure IZA). The prepared materials were characterized by 27Al MAS NMR, X-ray diffraction and scanning electron microscopy with microprobe rays. The pre-tramento proved to be the most appropriate and suitable temperatures are between 600 and 700?C. Observed the formation of zeolite A in all materials, reaching 52% crystallinity, and the presence of phase sodalite and amorphous material. The second study was the use of a highly reactive metakaolin originating from the Jari region in the synthesis of zeolite A by a new method of hydrothermal synthesis. The zeolite is obtained pure and highly crystalline employing the Jari kaolin calcined at 600 ? C for 2h when the transformation to metakaolin occurs. Get to zeolite phase A at 4pm. The best crystallization time was of 24 h afforded a crystallinity of 67.9%. The third study was the evaluation of the NaOH / metakaolin and crystallization time on the synthesis of zeolite NaA from a sample of kaolin waste, named Kaolin Coverage. The experiments were performed using statistical design (axial points) and rejoinder the center point. The samples were characterized by X-ray diffraction (XRD), scanning microscopic analysis and chemical analysis using an EPMA microprobe. The results showed that a relationship exists between the amount of NaOH added and the crystallization time. The experiment performed using the lowest ratio NaOH / metakaolin (0.5) and shorter (4 h) produced an amorphous material. The increase ratio of NaOH / metakaolin and crystallization time leads to formation of a more crystalline NaA phase, but the presence of phase with sodalite as impurities / Tr?s estudos foram realizados empregando rejeitos de caulins para a s?ntese da ze?lita A. O primeiro a s?ntese da Ze?lita A foi realizada utilizando-se um rejeito de caulim, gerado a partir do processo de beneficiamento de caulim para produ??o de papel, foi estudada. O rejeito de caulim foi ativado termicamente em um intervalo de temperatura de 550 a 800?C. Para efeito de compara??o foi realizada uma s?ntese padr?o de Ze?lita A (procedimento da IZA). Os materiais preparados foram caracterizados por RMN-MAS de 27Al, difra??o de raios X e Microscopia eletr?nica de varredura com microsonda. O pr?-tramento mostrou-se necess?rio e as temperaturas mais adequadas foram entre 600 e 700?C. Observou-se a forma??o da ze?lita A em todos os materiais, alcan?ando-se 52% de cristalinidade, al?m da presen?a da fase sodalita e de material amorfo. O segundo estudo foi o emprego de um metacaulim altamente reativo origin?rio da regi?o do Jar? na s?ntese da Ze?lita A atrav?s de um novo m?todo de s?ntese hidrotermal. A zeolita A ? obtida pura e altamente cristalina empregando o caulim da regi?o do Jar? calcinado a 600?C por 2h quando ocorre a transforma??o para metacaulim. Obtem-se a fase zeolita A em 4h. O melhor tempo de cristaliza??o encontrado foi de 24 h que proporcionou uma cristalinidade de 67,9 %. E o terceiro estudo foi a avalia??o da rela??o de NaOH / metacaulim e tempo de cristaliza??o na s?ntese da ze?lita NaA a partir de uma amostra de rejeito de caulim, nomeado como Caulim de Cobertura. Os experimentos foram realizados utilizando planejamento estat?stico (com pontos axiais) e treplica do ponto central. As amostras obtidas foram caracterizadas por difra??o de Raios-X (DRX), an?lises microsc?picas de varredura e an?lise qu?mica utilizando-se uma microssonda EPMA. Os resultados mostraram que existe uma rela??o entre a quantidade de NaOH adicionado e o tempo de cristaliza??o. Os experimento realizados utilizando a mais baixa rela??o NaOH / metacaulim (0,5) e menor tempo (4 h) produziu um material amorfo. J? o aumento da rela??o NaOH /Metacaulim e o tempo de cristaliza??o leva a forma??o de uma fase NaA mais cristalina, mas com a presen?a da fase sodalita como impureza

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / The present work deals about the synthesis and characterization of magnetic zeolites obtained by hydrothermal route using kaolin from Brazilian Northeast as silicon and aluminum source. By means of the X-ray diffraction technique it was possible to identify zeolite LTA and zeolite P1 as major crystalline phases for each synthesis, with low intensity peaks referent to unreacted quartz present in the kaolin used, which is in accordance to the. FTIR spectra; the nanoparticles were identified as magnetite, with low intensity peaks referent to goethite. In scanning electron microscopy, however, it was not possible to morphologically identify these minor components, while the zeolites showed well defined morphologies, presenting unchanged morphology when in the composites form, but with nanoparticles dispersed over their surface, as expected. From transmission electron microscopy it was observed that the nanoparticles were of ca. 50 nm. Magnetic measurements indicated magnetite presence with superior diameter to critical diameter to superparamagnetic particles and remanent magnetization. Thermogravimetric analyses showed for the composites, lower mass loss than compared to the pure zeolites what may be associated to the improvement of its thermal stability. Granulometric distribution indicated nanoparticles agglomeration in variable sizes, while zeolites formed agglomerates of ca. 10 Âm. Water softening was accomplished by using both zeolites, with high efficiency on Ca2+ removal and similar behavior between the zeolite and its respective composite, being the best result observed for zeolite A, with efficiency of 97,95%, reaching equilibrium in the first contact minutes. The dependence on mass studies also showed that zeolite A and its composite presented the best efficiency, whereas zeolite P achieved the same removal levels using corresponding zeolite masses (45 mg). This way, the proposed method for zeolites synthesis proved to be efficient, so that the use of a magnet is capable to attract them, leading their excellent separation from the aqueous medium with its ionic exchange capacity unaffected. / O presente trabalho trata da sÃntese e caracterizaÃÃo de zeÃlitas magnÃticas obtidas por impregnaÃÃo de nanopartÃculas de magnetita a zeÃlitas A e P, sintetizadas por mÃtodo hidrotÃrmico utilizando caulim branco do Nordeste brasileiro como fonte de silÃcio e alumÃnio. Por meio da tÃcnica de difraÃÃo de raios-X foi possÃvel identificar como fases cristalinas majoritÃrias a zeÃlita LTA e P1 para cada sÃntese, com picos de baixa intensidade referentes a quartzo, resistente ao processo tÃrmico de tratamento prÃvio do caulim, bem como nos espectros de infravermelho; as nanopartÃculas foram identificadas como magnetita, havendo ainda indÃcios da presenÃa de goethita em pequena quantidade. Nas anÃlises de microscopia eletrÃnica de varredura, entretanto, nÃo foi possÃvel identificar esses componentes minoritÃrios morfologicamente; enquanto que a morfologia das zeÃlitas mostrou-se bem definida, sem alteraÃÃes apÃs a formaÃÃo dos compÃsitos, apenas com nanopartÃculas espalhadas em sua superfÃcie, como desejado. A partir da microscopia eletrÃnica de transmissÃo, pÃde-se observar melhor a variaÃÃo de tamanho das nanopartÃculas, em mÃdia de 50 nm. Medidas magnÃticas das amostras com essa propriedade indicaram a presenÃa de magnetita com diÃmetro superior ao diÃmetro crÃtico para partÃculas superparamagnÃticas e magnetizaÃÃo remanente. As anÃlises termogravimÃtricas mostraram que a adiÃÃo das nanopartÃculas Ãs zeÃlitas diminuiu sua perda de massa diante do aumento de temperatura e as anÃlises de distribuiÃÃo granulomÃtrica indicaram a aglomeraÃÃo das nanopartÃculas em tamanhos variÃveis, enquanto que as zeÃlitas formaram aglomerados de aproximadamente 10 Âm. Os ensaios de abrandamento de Ãguas mostraram alta eficiÃncia das zeÃlitas em remover Ca2+, com comportamento similar entre a zeÃlita e o seu respectivo compÃsito, encontrando para a zeÃlita A o maior percentual de remoÃÃo, de 97,95 %, atingindo equilÃbrio nos primeiros minutos de aplicaÃÃo. Os estudos de massa tambÃm mostraram a eficiÃncia da zeÃlita A e de seu compÃsito, tendo a zeÃlita P se aproximado dos mesmos nÃveis de remoÃÃo em massas referentes a 45 mg de zeÃlita. Assim, o mÃtodo proposto para sÃntese das zeÃlitas magnÃticas mostrou-se eficiente, de modo que a utilizaÃÃo de um Ãmà à capaz de atraÃ-las facilitando a separaÃÃo do meio apÃs a aplicaÃÃo em meio aquoso e sua capacidade de troca iÃnica nÃo foi afetada.

Les systèmes de post-traitement qui combinent diverses fonctionnalités dans un même dispositif catalytique sont considérées comme une solution efficace pour réussir l’objectif définie par les restrictives futures normes qui régulent les émissions de l'industrie automobile. Ils permettent non seulement de réduire les coûts intrinsèques dus à l’encombrement mais aussi, dans certains cas, de favoriser les réactions catalytiques par des effets thermiques ou synergiques. Ce concept est particulièrement étudié pour les moteurs Diesel dont la ligne d'échappement peut comprendre jusqu'à quatre éléments. La réduction des NOx peut être réalisée par réduction catalytique sélective de l'ammoniac sur filtre (NH3-SCRF) en utilisant des catalyseurs à base de zéolite échangée par Cu ou Fe. Ce filtre à suie catalysé assume simultanément deux fonctions: l'élimination des particules et la réduction des espèces de NOx vers N2 et de l’eau. En ce qui concerne les catalyseurs SCR, la couche active est classiquement déposée sur les parois d'un substrat de grande porosité dont les canaux sont bloqués à des extrémités alternatives. Une porosité accrue du substrat du filtre (tel que la cordiérite ou SiC) est nécessaire pour permettre le dépôt de la quantité de phase de catalyseur nécessaire pour le traitement des émissions gazeuses en assurant une filtration efficace et sans produire un effet de contre-pression du system. En plus, il est nécessaire de remarquer que des nouvelles réactions se produiront dans ce système puisque la suie Diesel, le NOx et l'agent réducteur sont présents dans la même unité pour la première fois. Selon la littérature actuellement disponible, les polluants et la suie peuvent interagir de trois manières principales: 1) la suie bloque l'accessibilité du flux gazeux aux sites actifs «classiques» du catalyseur; 2) possibilité de réduction des NOx sur les particules de suie; et enfin, 3) la présence de suie affecte les performances des réactions SCR ou, au contraire, les réactions SCR affectent le processus d'oxydation des particules jusqu'à ce que la compétition pour le NO2 soit produite / Aftertreatment systems that combine various functionalities into the same catalytic device are considered to be an efficient solution to reach the target defined by the restrictive future emission standards that regulate the automotive industry emissions. They are able not only to reduce the intrinsic costs due to the packaging but also, in some cases, to promote catalytic reactions by thermal or synergistic effects. This concept is being particularly explored for Diesel engines whose exhaust line may comprise up to four separate elements. NOx abatement can be accomplished by ammonia selective catalytic reduction on filter (NH3-SCRF) using Cu or Fe-exchanged zeolite-based as catalysts. This catalysed soot filter assumes two functions, simultaneously: removal of particles and reduction of NOx species towards N2. Regarding the SCR catalysts, the active layer is conventionally deposited onto the walls of a high porosity substrate whose channels are blocked at alternative ends. An increased porosity of the filter (such as cordierite or SiC) substrate is required to allow the deposition of the amount of catalyst phase needed for the treatment of gaseous emissions while efficient filtration and without producing a backpressure effect. Furthermore, it is necessary to remark that new reactions will occur in this system as Diesel soot, NOx and the reductant agent are present in the same unit for the first time. Accordingly to the literature currently available, there are three main ways that NOx pollutants and soot may interact: 1) soot blocking the accessibility of gas flow to “classic” active sites of the catalyst; 2) possibility of NOx reduction takes place over the soot particles; and finally, 3) soot presence affects SCR reactions performance or, contrarily, SCR reactions affects PM oxidation process as far as competition for NO2 will be produced